So I'm mounting up my new S&S motor and I'm fitting the primary and clutch and working the motor a bit back and forth to look at alignments and oil starts leaking out of the crank breather. It looks like there is oil in the crankcase from when we first set it up with an oil tank. I'm surprised at the burping and wonder if this is not a sign something is assembled wrong. Any imput helpful. thanks

 

Is this an S&S EVO engine? We need more info for a accurate analysis. You cannot give too much information! What do you think would happen if you dropped your bike off at the shop and just told them "it's broken"?

Hmmm... new build, eh? Sounds like something was installed wrong. Send it back and have them do it right. Are the oil lines connected to the correct fittings? The oil pump check valve could be stuck open, too. That would cause oil to leak down into the crankcase. Then again, it might be fine once you crank it up. Check the above mentioned items first, though.

Let us know what you find out.

 

It's an S&S Evo 80" motor that was professionally built and balanced. I bought it as part of a project and I have the balance sheet. The motor was built at a local HD dealer in the Minneapolis area.

Since the pump is gravity fed, what stops the oil from draining from the tank into the crank? I'm guessing that oil has filled the crank somehow....

 

The term "professionally built" is relative. What's considered professional to one person may not be considered professional to another. From past experiences, with a few exceptions, I wouldn't call anything built at a dealership "professional". I have a lot more faith in an engine built by someone who owns an independent performance shop who has built many, many engines. And not using all H-D parts like the dealers usually do. In a nutshell, I don't trust much of anything, maintenance-wise, that comes out of a dealership's shop, except for maybe an oil change. Even then, I would double-check their work. Many of their techs are fairly fresh out of school and haven't gained the actual experience that comes with doing several rebuilds of different levels of performance.

To answer your question about the oil system, you can look in your HD factory service manual, it will show you the diagram for the oil system. That will answer your question. If you don't have that book, then GET IT ASAP! Yes, you have an S&S engine, but it's still an EVO, although there may be a few small differences. You need to have the manual if you are going to work on it.... period.

 

Like Spectrexx said. there is a check valve in the oil system that keeps the oil out of the crankcase when the motor is off. I believe it takes around 3 psi to open it.